New cytogenetic techniques have promoted progress in determining the role of chromosomal
abnormalities in the cause of congenital cardiac defects. Some patients with congenital cardiac
defect have a microdeletion within chromosomal region 22q11, and a majority of them are conotruncal
cardiac defects. To determine frequency in our population, we evaluated 36 patients with congenital
cardiac defects, 23 of them with conotruncal cardiac defects. Microdeletion of 22q11 was detected in
seven of 36 patients (19.4%), and in all deleted cases cardiac pathology was conotruncal.